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Damage evolution of tuff under cyclic tension-compression loading based on 3D digital image correlation
Engineering Geology ( IF 7.4 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.enggeo.2020.105736
Cancan Chen , Jiang Xu , Seisuke Okubo , Shoujian Peng

Abstract We have investigated the damage evolution and crack propagation of tuff rocks under axially cyclic tension–compression (T–C) loading with different amplitudes. The field of axial strains in the rock surface was obtained by three-dimensional digital image correlation (3D-DIC) method. The apparent strains were used to analyze the damage evolution along with the nucleation and propagation of microcracks until rock failure. The experimental results demonstrated that a local damage zone (LDZ) was formed when the loading amplitude exceeded a certain value, and the rock sample was prone to tensile failure under T–C cyclic loading. Based on arrangement of the virtual extensometers on the field of axial strains, the axial stress–strain curves, maximum axial strain, secant moduli, and dissipated energy evolution were obtained as a function of cycle number. It was observed that the variations in these mechanical parameters and dissipated energy significantly increased in the T–C cycle test with the increase in the loading amplitude. Particularly, due to obvious accumulation of residual compressive strain during the first cycle, the maximum tension stress increased, secant modulus decreased, and the dissipated energy evidently increased under tension during the second cycle. Furthermore, the mechanical parameters and dissipated energy evolution as a function of cycle number inside and outside the LDZ under 80% amplitude confirmed that the deformation mainly occurred inside the LDZ and the energy mainly dissipated for the nucleation and propagation of tensile microcracks vertical to the loading direction inside the LDZ during rock failure process.

中文翻译:

基于3D数字图像相关性循环拉压载荷下凝灰岩损伤演化

摘要 我们研究了不同振幅轴向循环拉压 (T-C) 载荷下凝灰岩的损伤演化和裂纹扩展。岩石表面轴向应变场是通过三维数字图像相关(3D-DIC)方法获得的。表观应变用于分析损伤演化以及微裂纹的成核和扩展直至岩石破坏。试验结果表明,当加载幅度超过一定值时,会形成局部损伤区(LDZ),岩样在T-C循环加载下容易发生拉伸破坏。基于轴向应变场上虚拟引伸计的布置,轴向应力-应变曲线、最大轴向应变、割线模量、和耗散能量演化是作为循环数的函数获得的。观察到这些机械参数和耗散能量的变化在 T-C 循环测试中随着加载幅度的增加而显着增加。特别是由于第一次循环残余压应变的明显积累,最大拉应力增加,割线模量降低,第二次循环受拉时耗散能明显增加。此外,
更新日期:2020-09-01
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